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目的探讨对各类不同性质的粉尘中游离二氧化硅(SiO_2)消解处理方法和影响游离SiO_2测定结果偏差的原因及解决方法。方法采用GBZ/T 192.4—2007焦磷酸质量法,根据粉尘样品的性质针对性地改变样品前处理、消解方法及消解温度控制。对样品消解液难溶胶状体的处理方法,游离SiO_2颗粒过滤时穿透渗出原因,分析质量控制等进行分析测定。结果粉尘样品的采集、消解方法、温度的控制、含难溶胶状物的处理、颗粒过滤时穿透渗出原因等本文均探讨出较好的解决方法;13种类型粉尘中游离SiO-2消解方法检测结果比对,无机化合物粉尘A、B组结果较接近,有机化合物粉尘A、B组结果对比有差别,但有机化合物粉尘经B组消解方法处理后,所得检测结果较为接近实际含量。游离SiO_2滤液第1次过滤收集回收率为61.0%～86.3%,第2次滤液过滤收集合并2次滤渣回收率为98.6%～99.5%。结论不同性质粉尘样品可以针对性地选择消解方法进行分析测定。焦磷酸法消解温度可以控制在240～250℃范围内保持15min进行消解。颗粒≤2μm的游离SiO_2滤液过滤收集时选择滤纸孔径在<2μm的定量滤纸或采用二次滤液收集合并灰化。
Objective To investigate the reasons and solutions to various types of diasporic treatment of free silica (SiO_2) in dusts and the influence of the determination of free SiO_2. Methods GBZ / T 192.4-2007 pyrophosphate quality method was used to change the samples pretreatment, digestion method and digestion temperature control according to the properties of dust samples. The sample digestion solution of non-soluble gel processing method, the penetration of exudation of free SiO 2 particles filtering reasons, analysis of quality control analysis. Results The methods of collecting, digesting, controlling temperature, treating with insoluble solutes, penetrating exudation of particle filtration and so on are all discussed in this paper. The comparison of test results shows that the results of inorganic compound dust A and B are close, and the results of organic compound dust A and B are different. However, the results of organic compound dust treated by group B digestion method are close to the actual content. The first SiO_2 filtrate filtrate collection recovery was 61.0% ~ 86.3%, the second filtrate was collected by filtration and the second residue recovery was 98.6% ~ 99.5%. Conclusion Different kinds of dust samples can be selectively analyzed by digestion method. Pyrophosphoric acid digestion temperature can be controlled at 240 ~ 250 ℃ for 15min for digestion. Particles ≤ 2μm free SiO_2 filtrate filter collected when the selection of filter paper with a diameter of <2μm quantitative filter paper or the use of secondary filtrate collected ashing.